Power AUD600 PCB photo shows, you are fixed a 0.22 ohm 2W x 3Nos. it is 0.1 ohm 2W x 3nos.(=0.04 Ohm)or 0.1 ohm 3W x 2Nos.(=0.05 Ohm)and AUD600 PCB MOSFET you fixed on top it is fixed on bottom for easy mounting on heat-sink.
do not connect 56K resistor near tlo71 ic and 4148 diode and MUR1560 for first setup.connect the power check freq.(@250KHz){with speaker 4/8 Ohm} and DC offset voltage(max. 50mv)
everything working fine then you connect 56K and again check DC Offset voltage.

using 27V supply 6A for 2 ohms 75V supply 16.6A for 2 ohms and 88V supply 19.5A for 2 ohms so you should adj. the sensing components
Over current (I) = 550mv/0.04 Ohm x 1k5+1k/1k = 34A (not for IRFP250 its for IRFB4227)
so you need to adjust resistor value to get 23A for peak current(75V supply) and 27A for 88V supply.
I = 13.75 x 1.5K+2.2K/2.2K = 23A change resistor value 1K to 2.2K to set 23A and 1K to 1.5K to set 27A
and for low supply like 27v only connect resistor 1.5K OC will be @13A

Regards
Manoj

thanks manoj i am using irfp260 i will decide on the voltage once i finish with the pcb. thanks for support .

thanks sir manoj
how can i findout how much is dc offset voltage ?
i do not know how and where i must conect the voltmeter for findout amount DC offset.
i am wating for 1K 1% resistor
this amp is for test now
i must change your pcb beacuse my ETD29 is sleeping form not standing and i will want to munting mosfet in top and conect a heatsink to them.
near TL071 we have 2 number off 4148. you mean i must disconect them from board befor test the amp ?

hi every one,
Greetings,
irs1500 problem i check with out speaker connection signal led is glowing when signal is give, then i will connect the speaker the signal led is glow all time and no output what is the problem?